358 The American Geologist. December, 1894 
some seem to think they know. In order to reach a reasonable 
explanation of the origin and formation of the shale partings 
we should, if possible, be able to answer the questions : where 
did the coal vegetation all grow or come from? and how was 
it put in place? But whether it grew on or about the spot 
where its remains now are, or was transported or sorted hy 
water in one of the several ways geologists have supposed 
(myself among them), we may, I think, take it for granted 
that the lower of these two shale-layers got there during a 
pause. — a temporary stoppage of the growth or accumulation 
of vegetable matter within the region affected by the slate- 
parting. However this may have been, we will proceed to 
look closely at the "slate" itself. As the appearance of the 
two slate-bands is identical it matters not to which the follow- 
ing description be applied: 
Description qfthi shale forming parallel bands in tin Pittsburg coal. 
Macroscopic. Very fine-grained, in fact granules of ground mass not 
distinguishable. Specks and streaks of coal. Often a brecciated ap- 
pearance, due to mottling. Should suppose the sediments had been 
•derived from clay-slate or still older muds. 
Texture. Homogeneous, compact. 
"Fracture. Irregular, splits roughly parallel with bedding planes 
Xlmosl free from joints. 
Streak. Pale, brownish gray. 
Luster. Earthy, dull. 
Taste. Sometimes salt or astringent ('.' alunogen). 
Color. At a distance, dark, brownish black or gray; close to. varie 
gated or mottled by numerous shades of gray, brown, etc., of which 
more further on. 
>,-. .'//•. Probably about 2.G0. 
Tfbn-plastic. 
Fossils. Flat, long leaf or reed-like, compressed forms of an obscure 
nature: many macrospores. Impressions on surfaces of SigiUaria, etc. 
[Stigmara never recorded in this seam.] 
The shale sometimes parts easily from the coal next it, but 
in other places the planes of demarkation are less pronounced. 
So far as my observations go, the shale bands only show ab- 
normal thickening in proximity to or in contact with faults 
or comparatively recent disturbances of the coal bed, where 
the cause is easily explained. The "cleat" in the band of 
coal between the two thin slates is the same as that of the 
lower and higher benches of the seam, viz., strikingly uni- 
form. 
